As time progresses, methods of diagnosing various human diseases are being continuously developed. Recently, progress is being made by adopting state-of-the-art imaging techniques in related arts and applying three-dimensional imaging techniques to tissues.
As the most universal and widely used of the methods of diagnosing diseases, histological analysis is used. Since this method is relatively simple and has high reproducibility and accuracy of test results, its targets and necessity have continuously increased. For example, when metastasis of a tumor in a peripheral tissue is distinguished after tumor tissue is removed in an operating room in which tumor surgery is performed, a part of the peripheral tissue is excised to be used to determine whether the tumor is or is not metastasized by histological analysis. Since this method determines whether an obtained sample is or is not metastasized, obtaining suitable tissue is absolutely important, and there is no choice but to depend on the experience of a skilled surgeon. In addition, since the histological analysis includes preparation of a specimen and staining, analysis results cannot be directly obtained in the operating room. Accordingly, development of a method of overcoming the above limits that is capable of easily and rapidly diagnosing a disease in real time is urgently needed.
As a new method of analyzing a living body, a method capable of easily detecting a target without excision of a tissue and several steps of dying and activation, and having high specificity with respect to target cells or bioactive substances, should be needed. A generally and widely used histological analysis includes: dehydrating a tissue which becomes hard by being fixed in a 4-10% (v/v) aldehyde solution for 24 hours with alcohol; immersing the tissue in a paraffin solution melted at 60° C. for 2 hours or more to penetrate paraffin into the tissue or freezing the tissue; forming a sample-resin block in which a sample tissue is well fused with a resin in a refrigerator using a freezable resin; cutting a section having a desired thickness (4-10 μm) with a sharp blade in a microtome, which is a section forming device, to obtain a sample section, and attaching the section to a glass slide; and removing and hydrating the resin; and finally performing several staining methods on the sample section to observe pathologic features (Journal of Neuroscience Methods, 26, 2, 1988, pp 129-132; Atherosclerosis, 27, 3, 1977, pp 333-338).
However, the histological analysis, which is an invasive analysis used only on an excised tissue, is relatively complicated, and thus is not suitable for rapidly diagnosing a disease. To overcome this problem, many researchers are actively studying direct observation of a tissue in a living body using bio-imaging equipment such as position emission tomography (PET) or computed tomography (CT). However, this equipment is generally diagnostic equipment used before surgery, and is not easily used in an operating room requiring speed. In addition, this equipment has problems regarding biocompatibility of a material and supply of external energy, and therefore it is necessary to develop a more practical bio-imaging technique.
To solve such problems, methods of coloring a quantum dot or fluorescent material-coupled antibody by radiating light thereto have been studied (Korean Patent Nos. 10-877187 and 10-522086 and Korean Patent Publication No. 10-2005-58431). However, the materials disclosed in these references are synthetic metal particles or chemical substances whose stability in a human body has not been proven, and which are thus are only used for in-vitro research.
Accordingly, there is strong demand for developing a method for easily and rapidly diagnosing various diseases in real time, which can solve fundamental problems of bio-imaging techniques, is very safe, can be used in an operating room, and can replace conventional histological analysis.